Perforations in the walls of internal organs and vessels may be naturally occurring, or formed intentionally or unintentionally. In order to permanently close these perforations and allow the tissue to properly heal, numerous tissue fixation devices and methods have been developed employing sutures, adhesives, clips, staples and the like. One class of such devices is commonly referred to as T-anchors, also known as tissue anchors or visceral anchors. An exemplary tissue anchor is disclosed in U.S. Pat. No. 5,123,914, the entire contents of which are incorporated herein by reference. Such tissue anchors have been very successful in medical procedures requiring visceral wall mobilization or wall apposition.
Tissue anchors typically include a crossbar or some anchoring member connected to a suture. The anchoring member and suture may take many forms, but generally a needle is used to pierce tissue and deliver the anchoring member on one side of the tissue, leaving the suture extending back to the other side of the tissue. The sutures of one or more tissue anchors are collected and connected together, such as through tying the sutures together. A significant level of skill and coordination is required by the medical professional to deploy and subsequently tie the sutures together, especially when the tissue site is difficult to access within the body, such as in endoscopic or laparoscopic procedures.
Medical delivery devices used to deliver the tissue anchors generally comprise a sheath and a needle. The sheath has a sheath lumen sized to slidably receive the needle. The needle has a needle lumen sized to slidably receive the tissue anchor. In addition, a stylet is slidably disposed within the needle lumen to assist in the deployment of the tissue anchors. The medical delivery device may also comprise a handle that is connected to the proximal ends of the needle, sheath, and stylet for relative axial movement of these components by the medical professional. During deployment, the distal end of the stylet engages and pushes the tissue anchor out of the distal end of the needle.
The medical delivery devices are generally operable between a delivery configuration and a deployed configuration. In the delivery configuration, the needle is substantially contained within the sheath lumen, and the stylet is positioned within the needle lumen such that the proximal end of the stylet projects beyond a proximal end of the sheath. The distal end of the stylet is spaced proximally of the distal end of the needle and the tissue anchor. In this configuration, the tissue anchor remains contained within the needle. A cap is typically connected to a proximal end of the stylet.
To move the delivery device to the deployed configuration, the cap is pressed to distally advance the stylet through the needle lumen. This causes the distal end of the stylet to engage the tissue anchor and move it distally until the anchor exits the needle lumen.
A problem concerning these medical delivery devices is premature deployment of the tissue anchor. When a doctor or nurse is holding the device, there is a risk that the cap will be inadvertently or mistakenly pressed, causing the anchors to be prematurely deployed. The prior art discloses various locking mechanisms that are used to prevent the stylet from advancing through the needle lumen. However, these locking mechanisms must typically be completely disconnected and removed from the medical delivery device prior to deployment. Consequently, the locking mechanisms are often misplaced or become contaminated. These locking mechanisms may also become broken during removal. If the medical delivery device is to be re-used in the same or a subsequent procedure, then the misplaced, contaminated, or broken locking mechanism cannot be utilized. Therefore, a need exists to allow the medical delivery device to operate in the deployed configuration without having to completely disconnect and/or remove the locking mechanism from the device.